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     azel - satellite predictions

     azel [ -d ] [ -l ] satellite1 [ -d ] [ -l ] satellite2 ...

     Azel predicts, in convenient form, the apparent trajectories
     of Earth satellites whose orbital elements are given in the
     argument files.  If a given satellite name cannot be read,
     an attempt is made to find it in a directory of satellites
     maintained by the programs's author.  The -d option causes
     azel to ask for a date and read line 1 data (see below) from
     the standard input.  The -l option causes azel to ask for
     the observer's latitude, west-longitude, and height above
     sea level.

     For each satellite given the program types its full name,
     the date, and a sequence of lines each containing a time, an
     azimuth, an elevation, a distance, and a visual magnitude.
     Each such line indicates that: at the indicated time, the
     satellite may be seen from Murray Hill (or provided loca-
     tion) at the indicated azimuth and elevation, and that its
     distance and apparent magnitude are as given.  Predictions
     are printed only when the sky is dark (sun more than 5
     degrees below the horizon) and when the satellite is not
     eclipsed by the earth's shadow.  Satellites which have not
     been seen and verified will not have had their visual magni-
     tude level set correctly.

     All times input and output by azel are GMT (Universal Time).

     The satellites for which elements are maintained are:

     sla,b,e,f,kSkylab A through Skylab K.  Skylab A is the labo-
               ratory; B was the rocket but it has crashed.  A
               and probably K have been verified.

     cop       Copernicus I. Never verified.

     oao       Orbiting Astronomical Observatory.  Seen and veri-

     pag       Pageos I.  Seen and verified; fairly dim (typi-
               cally 2nd-3rd magnitude), but elements are
               extremely accurate.

     exp19     Explorer 19; seen and verified, but quite dim
               (4th-5th magnitude) and fast-moving.

     c103b, c156b, c184b, c206b, c220b, c461b, c500b
               Various of the USSR Cosmos series; none seen.


     7276a     Unnamed (satellite # 72-76A); not seen.

     The element files used by azel contain five lines.  The
     first line gives a year, month number, day, hour, and minute
     at which the program begins its consideration of the satel-
     lite, followed by a number of minutes and an interval in
     minutes.  If the year, month, and day are 0, they are taken
     to be the current date (taken to change at 6 A.M. local
     time).  The output report starts at the indicated epoch and
     prints the position of the satellite for the indicated num-
     ber of minutes at times separated by the indicated interval.
     This line is ended by two numbers which specify options to
     the program governing the completeness of the report; they
     are ordinarily both ``1''.  The first option flag suppresses
     output when the sky is not dark; the second supresses output
     when the satellite is eclipsed by the earth's shadow.  The
     next line of an element file is the full name of the satel-
     lite.  The next three are the elements themselves (including
     certain derivatives of the elements).

     /usr/jfo/el/* - orbital element files

     sky (VI)

     J. F. Ossanna